The Nature of the Pest
Bugs, insects, and spiders are absolutely everywhere in the billions and it is said that wherever you go, you are always less than 2 metres away from a spider. While the majority of spiders are completely harmless, someone suffering from arachnophobia is going to be very unhappy to be sharing a house with them.
Eradicating pests permanently has always proved notoriously difficult. Bugs are part of a natural ecosystem and many of them such as bees perform essential tasks in pollinating out fruits, vegetables and flowers, though they do not make good housemates. Aside from the damage they can cause to your home, as termites alone cause five billion dollars in damages each year just in the USA, they can also spread diseases, so they need to be either eradicated or persuaded to move somewhere else.